Start by choosing your material. My material of choice is outgrown or worn out jeans. Decide on the size of your square, rectangle or whatever shape you plan to use. My fabric is cut up as follows:
Rectangles 29" x 7"
These yield a finished 28" x 6" rectangle after allowing for a 1/2 inch seam.
Squares 8" x 7"
These yield a finished 7" x 6" square after allowing for a 1/2 inch seam.
Half-Squares 4 1/2" x 6"
These yield a finished 3 1/2" x 6" half-square after allowing for a 1/2 inch seam.
How did I arrive at these measurements? The rectangles are the largest piece of unmarred denim I can harvest from the back of my hubby's worn out jean legs. The squares are the largest I can harvest from the front without a lot of waste. The half-squares are used just so I can stagger the rows of the quilt because I like the way it looks. They also allow me to harvest small pieces that would otherwise get thrown out. Make your life simple and make a cardboard template once you settle on a size.
Next decide on the size of your quilt. I'm not into reinventing the wheel. I peeked at the label on my winter comforter and discovered it was 84" x 92". Now I had a goal size. With that in mind I got my calculator out and started playing with the numbers. Use the finished size numbers for these calculations.
I discovered that with the sizes of fabric I cut, 90" (15 6" width pieces) x 98" (14 7" squares or 9 7" squares plus 2 half-squares plus 1 28" rectangle) would work best. Don't panic about the stuff in quotes, I promise it's going to make sense soon.
Now it's time to grab your graph paper and sketch out your plan. Use a pencil to do this or you'll go crazy. Write everything you've calculated out, you won't remember why you chose a particular measurement unless you do this. Don't get stressed, this should be fun.
Tomorrow, I'll talk about translating your plan from paper to fabric. I'll also add pictures of my work in progress.